Hygrometer



April 11, 1933. R. G. BATEsoN 41,903,617

HYGROMETER Filed Sept. 16, 1931 2 Sheets-Sheet l ,By Mu April 11,

R. G. BATESON HYGROMETER Filed Sept. 16, 1931 V2 Sheets-Sheet 2 /N VEN TOR 1MM @fam/9mm ATTORNEY Patented Apr. 1l, 1933 UNITED STATES RICHARD GORDON BATESON, OF PRINCES RISBOROUGH, BUCKS,v IEINGLANI'D HYGROMETER Application filed September 16, 1931, Serial No. 563,075, and in Great Britain SeptemberV A17; 1930.

This invention relates to hygrometers, and has for its object to provide an improved form of hygrometer of the wet and dry bulb thermometer type in which the relative hu- 5 midity is given as a direct reading.

The improved direct reading hygrometer which constitutes the present invention is based upon the principle of the nomogram or alignment chart and comprises one member D moving in a guide by amounts which are lfunctions of the dry bulb temperature, another member moving in a guide in the opposite direction by amounts which are functions of the Wet bulb temperature, and a link connected to each member and determining the humidity reading by its intersection with a curve.

When referring to moving in the opposite direction7 I means that one member moves in one direction for a rise in temperature and the other in the opposite direction for a rise in temperature, but both members are of course capable of movement in both directions according to whether the temperatures are rising or falling.

Referring to the accompanying drawings which illustrate the invention- Fig. 1 represents a front elevation of a preferred form of direct reading hygrometer embodying the invention,

Fig. 2 represents a rear elevation thereof.

In the form illustrated, the bulbs of the wet and dry bulb thermometers are connected to thin steel tubes of the Bourdon type and the bulbs and tubes are filled with mercury, the expansion and contraction of the mercury causing the closed end of the Bourdon tubes to move in and out, this movement being converted into rotary movement as is well known l0 in pressure and vacuum `gauges and automobile radiator thermometers.

The dry bulb thermometer C, which is ccnnected by a pipe a and a nipple connection Z) to the dry bulb, has a disk A on the rear of the apparatus, which disk is caused to partake of angular movement about its axis by changes of dry bulb temperature.

This disc A is connected by a flexible cable E with a carriage f movable between vertical guides g on the front ofthe apparatus and movements runs over guide pulleys (Z, e in passing from back to front. The wet bulb thermometer D has a disc B on the front of the apparatus and is connected by a pipe y' and a nipple Z1, to the wet bulb; the disc B is connected by l a cable G (which passes over a pulley k) to a carriage Z moving between vertical guides m.

The carriage f has pivoted thereto a link J which has a slot n passing over a wheel H 60 carried by the carriage Z. 'The link J engages a pivot K carried bya lever Mpivotally anchored at a point L and carrying a rack N engaging a pinion carried by a pointer p pro- Avided with la hair spring orlike backlash-f preventing means.

The thermometer discs A, Bl are so arranged that an increase of dry bulb temperature causes the carriage f to rise in its guide,

Lwhile an increase in wet bulb temperature V10 causes the carriage Z to move downwards in -its groove.

y The position of the point K therefore depends upon the combined eects of both i 375 If a series of readings representing different humidities be taken, and a straight edge laid across from dry bulbreading to wet bulb reading, it will be found that readings representing a definite humidity intersect at one 4'80 point, and in this way a humidity curve can be constructed between the two temperature scales.` The point K is arranged to travel along such a curve and with the proportions illustrated it is found that the correct curve is a circular arc with center L and radius LK.

Now it will be seen that if both thermometers are at the same temperature and are then heated or cooled the same amount, the position ofthe point K will not alter in'chang- 90 ing from one temperature to another, since that point at humidity is half-way between the two vert-ical grooves and since the novement of the tape E will be compensated -by an equal and opposite movement of the V495 tapeG.

It will be seen from the above description that the improved instrument is based upon the form of diagram known as the nomogram or alignment chart which is used 100 2 Y 1,9os,e17

The link J need not be rigid and could llame 5 be replaced by a cord stretched between the ,points F and H and the reading could be by the intersection of this oord upon a cum.

While the foregoing description is drawn 1 in terms of thermometers giving a purely linearv indication, the invention 1s also applicable to thermometers in which logarithmic lor vapour pressure scales are used. In "s thewit will-'be necessary tn make arrangel ments for the point K to travel over the appropriate curve such as by constraining it to in an appropriate cam slot. i i d h irect rea ing ygrometer comprising ai! vbulb thermometer, a guide, a memberwm in said guide, means to cause said meinberlin move by amounts which are functions otthe dry bulb temperature, a wet bulb l f Amunter, a sond guide, a member movs in'said second means for causing second movi member to :move b which are of the wet bul e ture and in a direction which is op toii'at in 'which said rst moving mem- AU is caused to move for a change of temperature of the same si a curved guidejay-,a link connecting saiii moving members said curvedv guideway, means is movable along said gudeway by said link, and a humidity indicator actuated'by said las; means.

irect reading' h grometer as claimed in him 1, wherein' guides are straight Y and the moving membersare caused to move i m them by amounts which bear linear rela 'titillev tothe whites of the dry and wet 3, hygrometerasclaimed in 1, wherein ,t ere 1s provided an india eating pointer and a pivoted arm connected and for causing said pivoted move so that a'point thereon coincides iiu'vfthc point of intersection of the link and direct rewdinghygrometer having a Rhum thermometer, a straight guide, a y moving nsaidfgude, means to cause iaidalide to moveby vamounts which are of the dry'zbub temperature, a wet iherlmomtelritmight guide parallel a slide moving in said secide means for caus` said second .V J Y lng H A move byA amounts which arev functhewet'bulb temperature and in a 'opposite tu that in which said first is use w move for a e se same sign, apiv arm, a .scal'e, a pointer moving over said fanfan alink said moving'slides and pivoted at an intermediate point to said pivoted arm.

In testimony whereof I have signed my s ecication.

D GORDON BATESON. 

